In general, a battery module includes a plurality of cells connected in series and/or in parallel. The battery module typically includes a cell assembly including a plurality of cells arranged in a direction, and a cover member having end plates capable of surrounding the cell assembly.
However, when the cells of the battery module are swollen due to overcharge, the end plates at two widthwise sides of the module bulge and expand outwards. In addition, the end plates at two lengthwise sides of the battery module are pressed due to the pressure of a large amount of gas generated from the cells during overcharge.
As an overcharge protection technology of a battery module, Korean Patent Registration No. 10-1500222 discloses a module structure in which swollen and expanded cells press a fluid pouch, the fluid in an inner space pushes a cap due to the expansion pressure of the cells to open a path and thus moves to an outer space to thrust a cutter, and a blade of the cutter breaks a welded point between a lead tab and a busbar to release electrical connection therebetween.
In addition, Korean Patent Registration No. 10-0881641 discloses a medium- or large-sized battery pack including an electrical connection member mechanically cut due to physical deformation of a battery cell when the battery cell expands by a threshold value or above, wherein the electrical connection member is a busbar, a wire, or a cable, and a part of the electrical connection member to be mechanically cut when the battery cell expands in volume is a connection part between electrode terminals and the busbar or the wire, a connection part between the cable and a tab terminal connected to the cable, or a connection part in the middle of the cable.